DBH, Canopy Coverage, and Distance from Tree to Sapling of Silver Maple Trees at York University

Data from 20 random Acer saccharinum (Silver Maple) trees were collected from York University's woodlot, Danby Woods. Four traits were measured: diameter at breast height (dbh) of tree, canopy coverage, distance to sapling, and dbh of sapling. Dbh was measured in cm and rounded to the nearest whole cm using a 20m transect tape measure. Canopy coverage was calculated as the percentage of sky present subtracted from 100% determined by the researcher by making a square with index fingers and thumbs; holding it up above researcher's head toward canopy and looking through the square. Distance to sapling was measured from the outermost point of the tree closest to the sapling to the outermost point of the sapling closest to the tree using a 20 m transect tape measure held along the ground. Saplings were defined in this experiment as any Silver Maple tree shorter than or equal to twice the height of the researcher.

本研究从约克大学丹比森林（Danby Woods）林地中随机选取20株银枫（Acer saccharinum，Silver Maple）个体，采集相关实验数据。共测定4项性状：母树胸径（diameter at breast height，dbh）、冠层覆盖率、幼树与母树的间距以及幼树胸径。胸径以厘米为计量单位，采用20米样带卷尺进行测量，结果修约至最接近的整厘米数值。冠层覆盖率的计算方式为：研究者以食指与拇指搭成正方形，将其举过头顶对准树冠并透过该正方形观测天空，以100%减去观测到的天空占比，所得结果即为冠层覆盖率。幼树与母树的间距以沿地面铺设的20米样带卷尺测量，测量起点为母树最靠近幼树的外缘点，终点为幼树最靠近母树的外缘点。本实验中将幼树定义为株高不超过研究者身高两倍的银枫个体。